1. Field of the Invention
The invention relates to a pressure plate arrangement for a motor vehicle friction clutch and in particular to a pressure plate arrangement with automatic wear compensation.
2. The Prior Art
A motor vehicle friction clutch is known from DE-A-35 18 781 (GB-A-2 176 256), the pressure plate arrangement of which comprises, as is customary, a clutch housing fastened to a flywheel, a pressure plate disposed on the clutch housing and fixed against relative rotation with it but axially displaceable, and a diaphragm spring clamped under prestress between the clutch housing and the pressure plate. The diaphragm spring presses the pressure plate via friction linings of a clutch disk against the flywheel. The pressure plate unit comprises an automatic wear compensation mechanism with an adjustment device disposed in the path of the support of the diaphragm spring between the diaphragm spring and the pressure plate, which causes the axial movement of the pressure plate away from the diaphragm spring when the friction linings are worn and the friction clutch is disengaged. For this purpose, the adjustment device has a plurality of wedge-shaped spreading bodies distributed in the circumferential direction which, during operation and with the friction clutch disengaged, wander under the effect of centrifugal force into the gap between the pressure plate and the diaphragm spring caused by wear. The known friction clutch has a friction-arresting path-limiting device, which limits the lifting path of the pressure plate in relation to the clutch housing and during the disengagement operation and, when a preset play of the path-limiting device is exceeded, makes it possible for the diaphragm spring to lift off its seat on the pressure plate, so that the wedge-shaped spreading bodies can enter between the diaphragm spring and the pressure plate for compensating the play.
It has been shown to be disadvantageous in connection with this known construction that automatic wear compensation is only possible after the play in the path-limiting device has been traveled and only in the fully disengaged state of the clutch. A construction of this type cannot be used in connection with a hydraulic disconnecting system, for example, because such disconnecting systems would already automatically compensate for small wear paths within the play without the wear compensation mechanism provided becoming effective.